Outline

Three human coronaviruses are known to exist: HCoV-229E, HCoV-OC43 and SARS-CoV. We identified a fourth human coronavirus (HCoV-NL63) using a new virus discovery method. The virus was isolated from a 7-month-old child suffering from bronchiolitis and conjunctivitis. The complete genome sequence demonstrates that this virus is not a recombinant, but a novel group 1 coronavirus. The in vitro host cell range of HCoV-NL63 is notable because it replicates on tertiary monkey kidney cells and the monkey kidney LLC-MK2 cell line. The viral genome contains distinctive features, including a unique N-terminal fragment within the spike protein. Screening of clinical specimens from individuals suffering from respiratory illness identified seven additional HCoV-NL63-infected individuals, indicating that the virus was widely spread within the human population.